General Information on Track Circuits - RGS Online

Railway Group Approved Code of Practice
GK/RC0752
Issue Two
Date December 1998
Page G2 of 3
5 IRJ Inspection
6 Performance Test
<strong>General</strong> <strong>Information</strong> on Track Circuits
5.1 Testing of IRJs
IRJs should be visually checked for indications of insulation deterioration, general
condition and rail burring over the insulation.
If an IRJ is suspect, a possession of the track circuits concerned should be
obtained and the IRJ tested for insulation break–down with the track circuits
taken out of service. The metallic components of the IRJ being tested should be
cleaned to allow a good electrical contact with the test leads. If the insulation
resistance between either plate and rail is less than 2kΩ at 50V, thew joint is
likely to fail or has partially failed and requires attention. The Engineering
Supervisor should be notified so that arrangements can be made with the
Permanent Way Engineer to replace the faulty IRJ.
In the case of d.c. track circuits, IRJ’s may be tested with the track circuits in
service under certain conditions. This procedure is described in GK/RC0755
Part F.
5.2 Prefabricated IRJs
Edilon and similar prefabricated IRJs must be tested with a 50V insulation tester
prior to installation in the track, taking care that the IRJ assembly is not in
contact with any conducting surface.
Test:
Withdrawn Document
Uncontrolled When Printed
a) Between the two rails.
b) Between both fishplates and the two rails.
c) Between each bolt and the two rails.
The minimum acceptable reading is 500kΩ..
a) The track circuit should be energised and adjusted in accordance with the
relevant section in this handbook. If difficulties are experienced, refer to the
Fault Finding Procedures.
b) Ensure that the polarity/phase is correct and that the correct electrical
stagger is achieved.
c) Track circuit interrupters must be tested by disconnection.
d) Ensure that all adjoining track circuits are energised. Remove the feed links
of the track circuit under test to check that only the correct track relay or
relays respond. Check that any remaining extraneous voltage on the track
relay does not exceed that permitted for the particular track circuit design
(see the Testing & Commissioning Part in the Code of Practice for the
relevant track circuit).
e) Set the shunt box to the minimum permitted drop shunt value, and apply
sequentially at all extremities and at selected places within any S & C, to
prove the functionality of the track circuit bonding; the correct track relay
must be seen to drop each time. For jointless track circuits, prove that the
theoretical extremities are the actual extremities.
G2 R A I L T R A C K